A manager records the repair cost for 14 randomly selected dryers. A sample mean of $88.34 and standard deviation of $19.22 are subsequently computed. Determine the 90% confidence interval for the mean repair cost for the dryers. Assume the population is approximately normal. Step 1 of 2 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

Hence the 90% confidence interval estimate of the population mean is

Step-by-step explanation:

Given that,  

Point estimate = sample mean = = 88.34  

sample standard deviation = s = 19.22  

sample size = n = 14  

Degrees of freedom = df = n - 1 = 13  

Critical value = df = 1.771

Margin of error

Margin of error = E = 9.10  

The 90% confidence interval estimate of the population mean is,  

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